Demonstration of intermittent ischemia and stunning in hibernating myocardium

Excerpt

Intermittent ischemia and stunning appear to characterize hibernating myocardium.1,2 In this report, we demonstrate the variable flow abnormalities that may underlie these phenomena. A 72-year-old woman underwent a rest/vasodilator stress ECG-gated ^99mTc-SPECT myocardial perfusion imaging (MPI). Image interpretation was consistent with a large anterior/anteroapical infarction with borderzone ischemia (Figure 1). Three days later, repeat rest/vasodilator MPI using ¹³N-ammonia and late gadolinium enhancement imaging (LGE) was performed simultaneously on a PET/MR (Biograph mMR, Siemens) as part of a research protocol to compare the accuracy of ischemia detection between SPECT and PET/MR. PET/MR MPI revealed extensive and severe anterior/anteroapical ischemia without infarction with resting and post-stress anteroapical hypokinesis (Figure 2A, B; Supplementary Movies 1-3). LGE PET/MR images showed no evidence of infarction in the area of ischemia detected by PET/MR (Figure 2C-E). The constellation of these findings allowed us to speculate that there was myocardial hibernation. Of note, absolute MBF calculated from the PET data demonstrated near similar resting flow values between the hibernating and normal myocardium with a paradoxical reduction in flow in the hibernating territory at stress, indicative coronary steal (Figure 3). Subsequent coronary angiography confirmed high grade LAD disease (Figure 4).

…